1. Field of the Invention
The present invention relates to a porcine reproductive and respiratory syndrome (PRRS). More specifically, the present invention relates to diagnostic and protective antigens and vaccine for the PRRS disease in pigs, and the methods of making and using the same.
2. Brief Description of the Prior Art
Porcine reproductive and respiratory syndrome is rapidly emerging as an economically devastating disease problem for U.S. and European swine producers. The syndrome was first described in the U.S. in 1987, with similar descriptions surfacing in Europe and Canada, two to three years later. The disease syndrome has been referred to by many different names including mystery swine disease, abortus blau, blue eared pig disease, porcine epidemic abortion and respiratory syndrome (PEARS), swine infertility and respiratory syndrome (SIRS). The name porcine reproductive and respiratory syndrome (PRRS) is employed hereinafter.
The etiological agent capable of reproducing the disease syndrome has been identified as a small enveloped spherical RNA virus, with an average virion diameter of 62 nm and a 25-30 nm core surrounded by an envelope. This virus has been tentatively grouped as a member of the genus Arterivirus within the Togaviridae family. The porcine reproductive and respiratory syndrome virus (PRRSV) isolate, described herein, fits this tentative classification and has been shown to reproduce the disease syndrome.
The disease syndrome associated with PRRSV is characterized by acute and chronic reproductive failure in adult female swine and severe to mild respiratory disease in young pigs. Reproductive failure is characterized by late term abortions resulting in increased incidence of mummified, stillborn and weak born pigs with markedly reduced chances for survival. Chronic problems with delayed return to estrus in infected sows has also been described. Respiratory disease sequela range from marked fever and interstitial pneumonitis to mild upper respiratory signs (i.e. sneezing, coughing, and nasal or ocular discharge) in young pigs. Recent (1990) serological and herd history studies indicate that at least 50% of U.S. swine herds have been exposed to PRRSV or have experienced reproductive failure and respiratory disease indicative of PRRSV infection.
Due to the recent emergence of this disease syndrome, studies on the pathogenesis, epidemiology and control of disease have been limited. As would be realized, an efficient propagation and processing of the antigens comprising PRRSV, will facilitate the development of a PRRSV vaccine as an aid in the prevention and control of porcine reproductive and respiratory syndrome.